This invention relates to electromagnetic projectile launcher systems and more particularly to such systems which utilize a single high current power supply to supply current to at least two pairs of launcher rails where the pairs of launcher rails form at least two bores of substantially different cross sectional area for the propulsion of projectiles having substantially different diameters and masses.
Conventional chemical propulsion artillery such as tank cannons are of relatively large bore size, in the vicinity of 110 millimeters, but must be capable of firing small diameter high velocity penetrators as well as large caliber high explosive projectiles. Though penetrators are generally of rather small diameter, the large bore size is required so that pressure generated by conflagration of the chemical propellant acts on a sufficiently large base area to develop adequate force to attain the desired projectile exit velocity in the available barrel length. In the case of penetrating projectiles, the propelling pressure is exerted against the base of a bore sealing sabot which encloses or carries the penetrator. This sabot structure falls away a short distance beyond the muzzle. Large caliber projectiles are inherently shorter and fill the bore, therefore no sabot is required. The important consideration for chemically propelled projectiles is that the breech pressure is limited for many reasons to a value on the order of 50,000 psi. In order to achieve adequate propulsion forces to accelerate the pay load, rather large diameter bores are required.
In a simple parallel rail electromagnetic launcher, the accelerating force is proportional to the square of the current with rather little dependence on the geometry of the bore configuration as long as it is approximately square. Thus a square bore launcher of for example 40.times.40 millimeters in size, will for a given current, produce about the same accelerating force as a square bore of doubled dimensions and thus four times the cross sectional area. Since penetrating projectiles are generally of small diameter and must frequently be fired in rapid succession, efficient cannon systems for firing penetrating projectiles such as anti-aircraft projectiles, will utilize the minimum adequate bore size so as to reduce barrel weight, allow faster aiming or laying, reduce armature or sabot weight, decrease barrel inertia effects during vehicle movement, etc. Thus an efficient artillery piece for the electromagnetic launching of small diameter projectiles will utilize small bores which will on the other hand be of insufficient size to launch the heavier and shorter large caliber projectiles.
In order to provide an electromagnetic launcher system which is capable of efficiently firing small diameter penetrating projectiles in rapid succession and large diameter projectiles at a slower repetition rate, a launcher constructed in accordance with the present invention utilizes a single kinetic energy-inductive pulse power system to supply launching current to two separate cannons. Therefore an electromagnetic projectile launching system in accordance with the present invention includes a single high current pulse power supply, at least two barrels each having at least one pair of conductive rails for accelerating projectiles, means for conducting current between the rails of each barrel and for propelling a projectile along the barrels, and means for commutating the current from the high current source to the breech end of each of the barrels. In an alternative embodiment, a single barrel can be utilized which includes at least two bores of subtantially different cross sectional area. Each of the bores includes at least one pair of projectile launching rails. In addition, means for conducting current between these rails and for propelling a projectile along the rails is provided. In each embodiment of this invention, augmenting rails can be utilized along the bore having the largest cross sectional area so that adequate forces to accelerate a heavier large caliber projectile can be obtained at about the same current levels as used for the penetrating projectiles in the small bores.